Semiconductor devices are requiring smaller dimensions as operational speeds of those devices increase. Currently, small dimensional devices require polishing in order to form the semiconductor devices. Single inlaid and dual inlaid interconnects are being used to provide the proper connections within the semiconductor device. A problem arises in that many interconnects include a barrier layer that is formed before forming the primary conductive fill material. When polishing the films to form the interconnect, typically scratches form within the underlying insulating layer. These produce visual and potentially electrical defects and are undesired.
In still other devices, the interconnects can include materials that are difficult to polish, such as platinum and iridium, because they are not readily oxidized or hydroxylated using typical polishing slurries. Therefore, polishing these materials generally relies more on the mechanical component of chemical-mechanical polishing compared to copper, aluminum, tungsten, or other materials that are more readily oxidized or hydroxylated. The greater mechanical component increases the likelihood of forming undesired scratches in underlying layers.
Attempts to remove of the scratches in the underlying layer have included using a short polish or removal step. The additional polishing or removal step increases cycle time or is only marginally effective in removing the scratches. Further, if the scratches are deep enough, too much of the underlying layer may need to be removed before the level of scratches is at an acceptable level.
Another attempt to reduce particles includes using a relatively soft poromeric pad, such as a Polytex.TM. polishing pad made by Rodel, Inc. of Newark, Del. instead of a relatively harder pad, such a Suba.TM. polishing pad that is also made by Rodel. While the relatively softer polishing pad may reduce the magnitude of the scratches, it does not eliminate them because the particles from the barrier layer are still dragged across the surface during polishing.